Many thanks for your kind comments and sorry my reply is coming so late - "real life" was a bugger the last two weeks.
@ WuZhuiQiu: The shore is done like the road, only that I have mixed several shades of blue paint into the acrylic paste instead of brown and I have left the sand out. It is tricky to make it look as rolling waves, I still need some practice here myself. Afterwards the foam on the waves is added, which is simply white paint and acrylic paste. When everything was dry, I gave it two or three layers of NOCH water-sourface paste, but to be honest PVA or even gloss varnish would have sufficed, I'm not so thrilled by the NOCH paste...
@ anevilgiraffe: Yes, I use the anchor-screws also to fasten the mat during play - which is especially helpful when you have placed items underneath to create hills. Due to the fastening the mat has a greater tension and the hills look better and hold the figures better. Instead of the anchoring screws, you could also use clamps. Without fastening, the mat will take some time to lie flat when it was rolled up for a long time. Placing heavy items on the edges helps. The smaller the mat is, the sooner it will lie flat: For a 60x60 mat that was rolled up for several month it takes about 10 minutes, for a very large (1,5mx2,5m) maybe bout an hour or two - but you can play on it after fice minutes, it just does not look completly plain.
@ Furt & Elk101: Thank you - but it really is pretty easy. The canvas is any painter canvas - at the beginning I've bought it on these large frames and cut it loose afterwards - this didn't requiring anchoring it on the table, but it was much more expensive then buying the stuff rolled up in bulk. You can use as flock everything you can get your hands on - from colored sawdust to static grass. I often buy anything in these model railroad-stores. As for the desert mat, there is flock on it - but brown one. The additional sand proved to be a design flaw - it does not look so good when not painted and falls off more easily than flock. So for the next desert map, I will use no additional sand that is not mixed in with acrylic paste and paint. Lastly the screws: I have flocked their heads, too, so they blend in rather well.
@ Kingscarbine: Silikone smells rather bad and is doing bad things to your brain cells. I'm going to stick with acrylic paste.
@ Zaheer: Yes, absolutly right. You really have to be quick about it and loose no time, the sooner you flock the mat after applying the paste, the better it will stick to it
I hope I've answered all your questions, if there are more please ask. Also, I'm ancious to see your results if you try it. Just remember, do not try it while your partner is at home...